Their chief concern: Some municipalities are underreporting pension liabilities; the ways in which those large costs are reported can vary widely from place to place.

“The purpose of the adjustments is to provide greater transparency and comparability in pension liability measures for use in credit analysis,” said Timothy Blake, a Moody’s managing director.

Cities on the list for review aren’t necessarily facing imminent downgrade, though their mere presence on that list makes it more likely.

Moody’s, as we speak, is re-examining these nine largest cities:

Chicago

BLOWING AWAY: Chicago’s credit rating was knocked down not one, not two, but three notches by Moody’s earlier this month. [Wikimedia Commons]

Yes, one of the nation’s largest cities could soon be headed down the same black hole as Detroit. Moody’s downgraded The Windy City’s credit rating by three notches last week, as a result of $19 billion in unfunded pension debt.

But that’s only one of several dark clouds on the horizon.

Another ? How about mayor Rahm Emanuel, President Obama’s former chief of staff, telling city employees they should sign up for the federal health insurance exchanges. It’s almost as if he might have known the city was running out of money to fund employee health care.

And there doesn’t figure to be much help coming from the state level. Illinois is grappling with a $97 billion unfunded pension liability of its own.

Portland, Ore.

PILING UP: Mount Hood looms over Portland, Ore., an apt metaphor for the pile of pension debt the city has accumulated. [Wikimedia Commons]

One has to wonder if Portland might deliberately drive itself into bankruptcy as part of a larger plan to become the hipster capital of the world.

Regardless, the largest city in Oregon is well on its way to financial trouble. Moody’s is reviewing the city’s credit rating for its general obligation bonds, but also for Portland’s tax obligation bonds, housing bonds and redevelopment bonds. The city has more than $453 million in unfunded pension debt.

Pew notes Portland “had virtually no asset” to offset unfunded liabilities of $2.3 billion in fiscal 2009 for its pension and disability plan for police and firefighters. The city is essentially paying for the retirement costs of those uniformed employees on a pay-as-you-go basis, which any actuary can tell you is a terrible idea.

Omaha, Neb.

SOMEWHERE IN MIDDLE AMERICA: Omaha is known for a certain investing guru, but the city could sure use some help from Warren Buffett. [Wikimedia Commons]

Maybe city officials can call Warren Buffett for some advice on handling large sums of money. Buffett’s hometown has managed to ring up more than $1.4 billion in pension liabilities, and it has only enough cash saved to pay about 43 percent of those costs, according to Pew.

But Omaha is not on Moody’s list, so a downgrade in the immediate future seems unlikely.

Minneapolis

DOWNGRADE IN THE GREAT WHITE NORTH: Minneapolis has run up more than $700 million in pension debt. [Wikimedia Commons]

One half of the Twin Cities could be facing a credit downgrade from Moody’s. St. Paul, it seems, is in the clear, for now.

Minneapolis has piled up more than $700 million in unfunded pension liabilities, prompting the ratings agency to take another look at the city. Moody’s is examining the city’s general obligation debt.

Cincinnati

GOING DARK: Cincinnati got hit with a credit rating downgrade from Moody’s last week. Could this midwestern city be the next Detroit? [Wikimedia Commons]

Moody’s downgraded Cincinnati just last week, after it was placed on the list of possible downgrades in April.

The ratings agency cited — surprise, surprise — pension debt as the main reason for dropping the credit rating for Cincinnati’s bonds.

“The outlook on the city of Cincinnati is negative, reflecting our expectation that the city will continue to face budgetary pressure stemming from required pension contributions to the City Retirement System and potential long-term pressure from its exposure to statewide, multi-employer, cost-sharing pension plans,” Moody’s wrote.

The city’s unfunded pension liability tops $700 million.

Providence, R.I.

HEAVEN HELP US: Providence might need some divine help to dig out from under one of the biggest per-capita pension debts in the nation. [Wikimedia Commons]

The capital of the nation’s smallest state is not facing additional scrutiny from Moody’s, but it makes our list for having one of the worst-funded pension systems of any major city in the U.S.

With a funding ratio — the percentage of pension debt versus current assets to pay — of 42 percent, Providence’s pension mess, per capita, is even worse than Chicago’s.

But Pew notes Providence has taken some steps in the right direction. The city suspended annual cost-of-living adjustments for retirees and now requires all former workers olden than 65 to switch to Medicare instead of receiving health benefits from the city. Ah, there’s nothing like being able to dump your aging population into a taxpayer-funding health-care system to save your own taxpayer-funded health care system.

Trenton, N.J.

TAKING TOO MUCH: The famous Lower Trenton Bridge reads “Trenton Makes, The World Takes,” but the New Jersey capital city has given away too much — to retired workers. [Wikimedia Commons]

Moody’s is reviewing general obligation bonds issued by Trenton’s public school system. A downgrade on those bonds would follow fast in the footsteps of a citywide downgrade in 2011.

Mercer County, which houses Trenton, was bumped down a notch by Moody’s earlier this year.

Santa Fe, N.M.

WHATS GOING ON IN NEW MEXICO? Santa Fe was one of three cities (plus Santa Fe County) Moody’s put on notice earlier this year. [Wikimedia Commons]

In putting Santa Fe “on notice” a few months ago, Moody’s noted the severity of the city’s pension problems. Moody’s ranked the city of Santa Fe as the worst in the country, saying it has net pension liabilities equal to six times its operating revenue.

“Their calculation is skewed,” Marcos Tapia, noting the city is not a Moody’s client. “We’ve told Moody’s, we need you to retract this, you need to correct this.”

Moody’s is also reviewing two other cities in New Mexico and the credit rating for Santa Fe County.

Charleston, W.Va.

HARD ROAD AHEAD: With an impoverished and shrinking population, West Virginia will have a hard time paying off its public pension debt — and Charleston is in worse shape than any other major city. [Wikimedia Commons]

Like Providence, Charleston is another state capital that makes our list despite not attracting direct scrutiny from Moody’s — right now. The reason? Charleston has the worst-funded pension system of any major city in the United States, with only 24 percent of the necessary funds to cover more than $337 million in pension debt.

Like Chicago, Charleston won’t be able to look to the state for help. West Virginia is dealing with its own pension crisis — only Illinois has a lower funded ratio of its state pension plans.

Digging out of the hole is made harder by the high levels of poverty and a declining population, a lesson Detroit learned the hard way.

Eric Boehm is a reporter for Watchdog.org . Contact him at [email protected] Follow him on Twitter @EricBoehm87